Kilikowska Adrianna, Mioduchowska Monika, Wysocka Anna, Kaczmarczyk-Ziemba Agnieszka, Rychlińska Joanna, Zając Katarzyna, Zając Tadeusz, Ivinskis Povilas, Sell Jerzy
Department of Genetics and Biosystematics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
Department of Marine Plankton Research, University of Gdansk, Piłsudskiego 46, 81-378 Gdynia, Poland.
Life (Basel). 2020 Jul 21;10(7):119. doi: 10.3390/life10070119.
Mussels of the family Unionidae are important components of freshwater ecosystems. Alarmingly, the International Union for Conservation of Nature and Natural Resources Red List of Threatened Species identifies almost 200 unionid species as extinct, endangered, or threatened. Their decline is the result of human impact on freshwater habitats, and the decrease of host fish populations. The Thick Shelled River Mussel Philipsson, 1788 is one of the examples that has been reported to show a dramatic decline of populations. Hierarchical organization of riverine systems is supposed to reflect the genetic structure of populations inhabiting them. The main goal of this study was an assessment of the genetic diversity in river ecosystems using hierarchical analysis. Different molecular markers, the nuclear ribosomal internal transcribed spacer ITS region, and mitochondrial DNA genes ( and ), were used to examine the distribution of among-population genetic variation at multiple spatial scales (within rivers, among rivers within drainages, and between drainages of the Neman and Vistula rivers). We found high genetic structure between both drainages suggesting that in the case of the analyzed populations we were dealing with at least two different genetic units. Only about 4% of the mtDNA variation was due to differences among populations within drainages. However, comparison of population differentiation within drainages for mtDNA also showed some genetic structure among populations within the Vistula drainage. Only one haplotype was shared among all Polish populations whereas the remainder were unique for each population despite the hydrological connection. Interestingly, some haplotypes were present in both drainages. In the case of populations under study, the Mantel test revealed a relatively strong relationship between genetic and geographical distances. However, in detail, the pattern of genetic diversity seems to be much more complicated. Therefore, we suggest that the observed pattern of genetic diversity distribution is shaped by both historical and current factors i.e. different routes of post glacial colonization and history of drainage systems, historical gene flow, and more recent habitat fragmentation due to anthropogenic factors.
珠蚌科贻贝是淡水生态系统的重要组成部分。令人担忧的是，国际自然保护联盟濒危物种红色名录将近200种珠蚌科物种列为灭绝、濒危或受威胁物种。它们数量的减少是人类对淡水栖息地的影响以及寄主鱼类种群减少的结果。厚壳河蚌（菲利普松，1788年）就是其中一个种群数量急剧下降的例子。河流系统的层次结构被认为反映了栖息其中的种群的遗传结构。本研究的主要目标是通过层次分析评估河流生态系统中的遗传多样性。使用了不同的分子标记，即核糖体核糖核酸内转录间隔区ITS区域和线粒体DNA基因（和），来研究在多个空间尺度上（河流内部、流域内不同河流之间以及涅曼河和维斯瓦河的流域之间）种群间遗传变异的分布情况。我们发现两个流域之间存在高度的遗传结构，这表明在所分析的种群中，我们至少应对的是两个不同的遗传单元。线粒体DNA变异中只有约4%是由于流域内种群间的差异。然而，对线粒体DNA在流域内种群分化的比较也显示出维斯瓦河流域内种群间存在一些遗传结构。尽管存在水文联系，但所有波兰种群中仅共享一种单倍型，而其余单倍型在每个种群中都是独特的。有趣的是，有些单倍型在两个流域中都存在。在所研究的种群中，曼特尔检验揭示了遗传距离和地理距离之间存在相对较强的关系。然而，详细来看，遗传多样性模式似乎要复杂得多。因此，我们认为观察到的遗传多样性分布模式是由历史和当前因素共同塑造的，即不同的冰后期殖民路线和排水系统历史、历史基因流以及近期由于人为因素导致的栖息地破碎化。
